A protective hood made of an elastic material has become known from DE 27 21 727 C2. The prior-art protective hood is used for protection against undesired substances in an outside atmosphere, and it has an oxygen-breathing apparatus, through which a user of the hood can breathe air or oxygen in a suitable manner. The hood consists of an elastomeric material, which is in tight contact with the head of the user of the hood and is provided for different sizes of heads. When a uniform hood size is used for different head sizes, compromises must inevitably be made in the case of the prior-art protective hood. Good fitting shape is achieved, in general, for an average head size. If the same hood is placed on a larger head, it is generally seated too tightly. Since the hood is also stretched more extensively when placed on the larger head, the material of the hood can undergo plastic deformation, and the hood will no longer be in uniform contact with the face of the user of the hood. If, in contrast, the hood is used by a person with a smaller head, it will frequently fit loosely. If the hood has undergone plastic deformation when put on, or it is generally seated loosely on the head of the user of the hood, an oxygen-breathing apparatus located in the hood usually must also be secured with additional straps. This reduces the wear comfort. In addition, the head area and the neck area are designed as separate components in the prior-art hood, and they are connected to one another at a seam area. Such connection areas are especially prone to tearing; thus, a tear may develop in the hood at the connection area when put on.